Chlorophyll, fenoxaprop, pinoxaden, seedling growth, whole plant assay

Fenoxaprop-P-ethyl resistant populations of Phalaris minor Retz. have been observed in wheat fields in India. A quick and accurate means of confirming resistance is necessary to take timely management decisions. Seedling growth and chlorophyll development as affected by the doses of herbicides in Petri dishes were estimated in this study. ED50 values obtained for chlorophyll development compared to the seedling growth, discriminated the two feoxaprop resistant populations from each other and from the susceptible population better and provided a close relationship with the whole plant assay. The efficacy of pinoxaden against these populations was also studied based on this parameter. The parameter has the potential to be utilized for early detection of fenoxaprop resistance in P. minor populations, and to screen these on a large scale